Sounds like a neat project. As far as I am aware the GTI-R oil pump is a one-model design. I have checked the FAST parts database for you and found the following part numbers:
15020-54C00 - Rotor Set, Oil Pump (consists of inner and outer gear)
15021-54C00 - Inner gear (aug. 90 to aug. 92)
15021-54C01 - Inner gear (aug. 92 or later)
15023-54C00 - Outer gear
I checked for interchangeability and alternate applications of the same parts but found none. Under 15,000 GTI-R were made, with the newest one being just about 20 years old so it may be difficult to source these parts (particularly in any kind of quantity). The only reputable source I came across was
FRSport, but they are only selling the front cover assembly for the GTI-R which is about 10 times the price of the pump.
The P11 pump may prove an easier part to source, unfortunately the only engine that lists PNs for the pumps is the SR20VE (Sep. 97+).
15020-1N501 - Rotor Set, Oil Pump
This part number is used in quite a few applications mainly in the SR20VE but also in the SR16VE in the B14 and B15 and the YD22 and YD25 diesel engines in cars like the U30 and Y11. I haven't seen much of a supply of these in the US though.
A better option may be a pump from a US market SR such as the SR18DE in the B13:
15020-53J00 - Rotor Set, Oil Pump
This pump is available readily from most Nissan dealers,
Courtesy Parts has it listed for under $20. I'm not sure precisely what the differences are between these gear pumps. Good luck with your project.